RAFT Miniemulsion polymerization of styrene-co-butyl acrylate. A synthetic route to precise copolymer structure

In this study, an addition–fragmentation chain transfer agent (methyl 3-[(morpholin-4-ylcarbonothioyl) thio] propanoate) was used to synthesize Poly (St-co-BA) nanospheres via the miniemulsion polymerization. Well-defined Poly (St-co-BA) with a higher number-average molecular weight (Mn) and a lower polydispersity index (PDI, 1.4–1.7) was firstly obtained via reversible addition–fragmentation chain transfer (RAFT) process. The co-polymerization displays the characteristics of controlled/living radical polymerization as evidenced by pseudo first-order kinetics of polymerization, linear evolution of molecular weight with increasing monomer conversion, and narrow PDIs. The polymer samples have been analyzed via 1H-NMR spectroscopy to obtain the copolymer composition. In this work, the effect of initiator/RAFT agent ratio on specificity of the final copolymer was investigated. Polydispersity index (PDI) and particle size distribution decreased with increasing RAFT agent amount. By decreasing initiator/RAFT agent ratio, reaction conversion and rate decreased, which exhibits living polymerization behavior as expected before. The best result obtained when initiator/RAFT agent molar ratio was 0.55